A discovery in our laboratory of the phosphorylation of 5-BrdC in HSV infected cells will be extended towards the goal of highly selective chemotherapy of systemic, ocular, and cutaneous HSV infections. 5-halo dC analogs in combination with H4U (an inhibitor of cytidine deaminase) should be readily permeable to cells, not undergo catabolism (they are not substrates for uridine or dT phosphorylase) and, from studies in progress, are essentially not toxic to uninfected cells since such cells lack BrdC kinase. The analogs are highly inhibitory to HSV-1 and -2 in infected cells. We will determine if cells containing Herpes zoster, Epstein-Barr, Pseudorabies, Cytomegalo, Marek's disease, Lucke-Frog virus possess BCdR kinase. With a new assay we developed we will determine if unlabelled ICdR, 5-haloaraC, 5-CH3araC, 5-CH3-, 5-ethyl-, and 5-trifluoromethyl-dC are substrates of the HSV kinase. Analogs resistant to deamination at the nucleoside level will also be tested. We will test cells obtained from patients with cervical carcinoma, nasopharyngeal carcinoma, infectious mononucleosis and Burkitt's Lymphoma for this unique kinase activity. We will use an in vitro assay that measures collective properties of tissues and an autoradiographic assay using H3-CH3CdR to detect the unique kinase activity in cell populations where the activity may reside in a minor fraction of 'influential' cells. The unique kinase of HSV will be the basis for selecting HSV transduced and transformed cells by using CH3CdR plus H4U to rescue aminopterin-inhibited cells; the tumorinogenicity of these cells will be determined. We will determine whether inactivated virus can transform cells and whether BrdC plus H4U can induce edogenous virus in tissue culture. Enzymological studies on the purified pyrimidine deoxynucleoside kinase will enable us to determine the nature of this unique activity and to guide a chemotherapeutic approach to HSV diseases. Preliminary experiments with a mouse encephalitis model indicates that BrdC plus H4U given as a single IP injection daily for four days results in greater than 40 percent survival (at 6 months) in mice receiving greater than 1000 LD50 of virus, whereas 97 percent mice receiving BrdC alone are dead within 4 days and all receiving BrdC alone are dead within 7 days.